TY - JOUR

T1 - Adaptive strategies of sponges to deoxygenated oceans

AU - Micaroni, Valerio

AU - Strano, Francesca

AU - McAllen, Rob

AU - Woods, Lisa

AU - Turner, John

AU - Harman, Luke

AU - Bell, James J.

PY - 2022/3/1

Y1 - 2022/3/1

N2 - Ocean deoxygenation is one of the major consequences of climatechange. In coastal waters, this process can be exacerbated byeutrophication, which is contributing to an alarming increase in the so called“dead zones” globally. Despite its severity, the effect of reduceddissolved oxygen has only been studied for a very limited number oforganisms, compared to other climate change impacts such as oceanacidification and warming. Here we experimentally assessed theresponse of sponges to moderate and severe simulated hypoxic events.We ran three laboratory experiments on four species from two differenttemperate oceans (NE Atlantic and SW Pacific). Sponges were exposedto a total of five hypoxic treatments, with increasing severity (3.3, 1.6,0.5, 0.4 and 0.13 mg O2 L-1, over 7–12 days). We found that spongesare generally very tolerant of hypoxia. All the sponges survived in theexperimental conditions, except Polymastia croceus, which showedsignificant mortality at the lowest oxygen concentration (0.13 mg O2 L-1, lethal median time: 286 h). In all species except Suberites carnosus,hypoxic conditions do not significantly affect respiration rate down to 0.4mg O2 L-1, showing that sponges can uptake oxygen at very lowconcentrations in the surrounding environment. Importantly, spongesdisplayed species-specific phenotypic modifications in response to thehypoxic treatments, including physiological, morphological, andbehavioural changes. This phenotypic plasticity likely represents anadaptive strategy to live in reduced or low oxygen water. Our resultsalso show that a single sponge species (i.e., Suberites australiensis) candisplay different strategies at different oxygen concentrations. Comparedto other sessile organisms, sponges generally showed higher tolerance tohypoxia, suggesting that sponges could be favoured and survive infuture deoxygenated oceans.

AB - Ocean deoxygenation is one of the major consequences of climatechange. In coastal waters, this process can be exacerbated byeutrophication, which is contributing to an alarming increase in the so called“dead zones” globally. Despite its severity, the effect of reduceddissolved oxygen has only been studied for a very limited number oforganisms, compared to other climate change impacts such as oceanacidification and warming. Here we experimentally assessed theresponse of sponges to moderate and severe simulated hypoxic events.We ran three laboratory experiments on four species from two differenttemperate oceans (NE Atlantic and SW Pacific). Sponges were exposedto a total of five hypoxic treatments, with increasing severity (3.3, 1.6,0.5, 0.4 and 0.13 mg O2 L-1, over 7–12 days). We found that spongesare generally very tolerant of hypoxia. All the sponges survived in theexperimental conditions, except Polymastia croceus, which showedsignificant mortality at the lowest oxygen concentration (0.13 mg O2 L-1, lethal median time: 286 h). In all species except Suberites carnosus,hypoxic conditions do not significantly affect respiration rate down to 0.4mg O2 L-1, showing that sponges can uptake oxygen at very lowconcentrations in the surrounding environment. Importantly, spongesdisplayed species-specific phenotypic modifications in response to thehypoxic treatments, including physiological, morphological, andbehavioural changes. This phenotypic plasticity likely represents anadaptive strategy to live in reduced or low oxygen water. Our resultsalso show that a single sponge species (i.e., Suberites australiensis) candisplay different strategies at different oxygen concentrations. Comparedto other sessile organisms, sponges generally showed higher tolerance tohypoxia, suggesting that sponges could be favoured and survive infuture deoxygenated oceans.

KW - climate change, Porifera, marine benthic hypoxia, hypoxic events, oxygen depletion, eutrophication, phenotypic plasticity, evolution

U2 - 10.1111/gcb.16013

DO - 10.1111/gcb.16013

M3 - Article

VL - 28

SP - 1972

EP - 1989

JO - Global Change Biology

JF - Global Change Biology

SN - 1365-2486

IS - 6

ER -